1. Field of the Invention
The present invention relates to the manufacture of ophthalmic lenses. Specifically this invention relates to a dual ophthalmic lens machining platform and a method of simultaneously manufacturing pairs of ophthalmic lens.
2. Background Information
In the art of ophthalmic lens manufacture, finished ophthalmic lenses are usually made from finished uncut lenses or from semi-finished lens blanks. Finished uncut lenses are lenses that are optically finished on both front and back surfaces and only need to be edged to the proper shape and edge contour to become finished lenses. Semi-finished lens blanks have optically finished front surfaces; however, the back surfaces of these blanks need to be generated and fined and are then polished and/or coated to produce finished uncut lenses. The finished uncut lenses are then edged to the proper frontal shape and edge contour to fit into spectacle frames or other mounting structures. Within the meaning of the present application the terms spectacle, eyeglasses, or glasses can be used interchangeably. Single vision lenses that are outside the normal range of inventoried finished uncut lenses, and most multi-focal lenses, are made from semi-finished lens blanks. Semi-finished lens blanks are made with various front surface curve radii, and have various topographies including spherical, aspheric, hyperbolic, irregular aspheric such as progressive add lenses, and poly-spheric, such as executive type segmented bifocals and trifocals. Any specific semi-finished lens blank can be finished into a range or species of finished lens whereby each blocked lens blank is associated with a species of eyeglass prescriptions.
In order to generate a desired lens according to a specific prescription, calculations are required to determine the topography of the back surface of the lens. Such calculations typically involve variables that include the front surface radii of the semi-finished blank, the index of refraction of the lens blank material, prescription values of the desired lens, statutory values regarding minimum lens thickness, and the physical dimensions of the frame or mounting structure. In the art, various mechanisms have been devised to accomplish the physical process of producing a back surface of optical quality. Most of these methods begin by generating a back surface that approximates the desired back surface topography and surface smoothness. This approximate surface is then fined to a more perfect approximation in both curvature and surface smoothness. After the appropriate accuracy and smoothness is achieved in the fining process, the surface is then polished or surface coated to produce a surface of optical quality. The optically finished lens blank is then edged to the proper shape and edge profile to fit into the frame for which it was made. Finished lens may be further coated with tinting coatings, photo-chromic coatings, scratch resistant coatings (i.e. hard coats).
Many business entities that sell ophthalmic lenses do lens finishing as a profit center activity and as a way to expedite delivery of single vision lenses. Only a small percentage of these entities also do surfacing of ophthalmic lenses. The business volume of most of these entities cannot justify the costs of acquiring and operating a conventional surfacing laboratory as known in the art. Surfacing laboratory setup costs have heretofore been several times the cost of setting up a laboratory for edging only.
Hiring qualified technicians for ophthalmic lens finishing or training personnel to perform ophthalmic lens finishing is relatively easy. However, hiring and training optical technicians to operate a surfacing laboratory is not easy. In many communities it is very difficult to find personnel that are trained in surfacing on conventional equipment. Technicians who are qualified to do surfacing are generally remunerated at higher pay scales than technicians skilled only in edging.
In addition to the significantly higher equipment and personnel costs of a surfacing lab, there are also higher ongoing costs for the additional lab space required. At least several hundred square feet of operational space and storage space have heretofore been required for a full service surfacing and edging ophthalmic lens laboratory. Consequently there is a need for a system and method of ophthalmic lens manufacture that would significantly reduce the investment required to acquire a surfacing and edging laboratory. There is a further need for a system and method of ophthalmic lens manufacture that significantly reduces the costs associated with operating a surfacing and edging laboratory. Further, there is a need for a system and method of ophthalmic lens manufacture that is operative to perform surfacing and edging by an operator with little skill in the art.
Further, in the prior art, the processes of surfacing and edging are done on at least two separate machines. In the prior art, blocking for surfacing and edging required two separate blocking devices. Also in the prior art, the individual processes of lap tool surfacing and lens cribbing and safety beveling and edge grooving and edge polishing and lens engraving each requires its own machine or device or machine augmentation. Consequently, there is therefore a need for a system and method of ophthalmic lens manufacture that reduces the need to employ a plurality of expensive and complex machines to manufacture lenses.
Prescription lenses for patients are generally generated in pairs (i.e. right and left lenses) for a spectacle frame. Prior art systems typically generate each lens independently. Production cycle times for generating lenses may be reduced by employing multiple, independent, surfacing and edging machines in the laboratory to generate pairs of lenses, however duplication of equipment at least doubles the acquisition and operational costs of the laboratory. Thus there exists a need for a system and method of ophthalmic lens manufacture that provides for reduced production cycle times for pairs of prescription lens without significantly increasing costs for the laboratory.